Is it possible to use Firebase Remote Config without having Google Play Services installed (aosp) on the device?
I did follow this setup in my android project: (via https://firebase.google.com/docs/android/setup):
- added classpath 'com.google.gms:google-services:4.3.3' into main gradle file
 - added implementation 'com.google.firebase:firebase-config:19.1.3' and 'apply plugin: 'com.google.gms.google-services'' into app gradle file
 
It does compile, but when I initially start the app fetchAndActivate does not succeed, because task results with after calling fetch():
MISSING_INSTANCEID_SERVICE (Failed to get Firebase Instance ID token for fetch)
  firebaseRemoteConfig = FirebaseRemoteConfig.getInstance();
        FirebaseRemoteConfigSettings.Builder configBuilder = new FirebaseRemoteConfigSettings.Builder();
        configBuilder.setMinimumFetchIntervalInSeconds(3600);
        firebaseRemoteConfig.setConfigSettingsAsync(configBuilder.build());
        HashMap<String, Object> defaults = new HashMap<>();
        defaults.put("variant", "basic");
        startActivity(new Intent(getApplicationContext(), CarLauncherBasic.class));
        firebaseRemoteConfig.setDefaultsAsync(defaults);
        firebaseRemoteConfig.fetchAndActivate()
                .addOnCompleteListener(this, new OnCompleteListener<Boolean>() {
                    @Override
                    public void onComplete(@NonNull Task<Boolean> task) {
                        if (task.isSuccessful()) {
                            boolean updated = task.getResult();
                            Toast.makeText(MainActivity.this, "Fetch and activate succeeded",
                                    Toast.LENGTH_SHORT).show();
                        } else {
                            Toast.makeText(MainActivity.this, "Fetch failed",
                                    Toast.LENGTH_SHORT).show();
                        }
                        String variant = firebaseRemoteConfig.getString("variant");
//
                    }
                });
    }